Blackberry plant named ‘Chesapeake’

ABSTRACT

The present invention is a new and distinct thorny blackberry cultivar named ‘Chesapeake’, which is capable of producing very large fruit in the spring midseason, the fruit being much larger and similarly durable than that of the standard cultivars. The cultivar is characterized by moderate suckering ability, recurved thorns and its very flavorful fruit which is edible even when the fruit is immature.

GENUS AND SPECIES OF THE CLAIMED PLANT

Rubus hybrid.

VARIETY DENOMINATION

‘Chesapeake’.

FIELD OF THE INVENTION

This invention concerns a new and distinct cultivar of thorny blackberryplant with a botanical name of Rubus argutus×R. cuneifolius L.

DESCRIPTION OF RELATED PRIOR ART

Several cultivars of thorny blackberry plants are known. ‘Chesapeake’may be distinguished from its parent, ‘Shawnee’ (U.S. Plant Pat. No.5,686) and other large fruited thorny blackberry cultivars such as‘Kiowa’ (U.S. Plant Pat. No. 9,861) by the recurvature of its spines andflavor of its fruit. It may be distinguished from ‘Black Butte’(unpatented) by the type of spines and its erectness, compared to thesemi trailing habit of the large fruited ‘Black Butte’. Fruit size andflavor distinguishes ‘Chesapeake’ from all other thorny blackberrycultivars known to us, including ‘Choctaw’ (U.S. Plant Pat. No. 6,678),‘Illini Hardy’ (U.S. Plant Pat. No. 8,333), ‘Raven’ (unpatented) and‘Ranger’ (unpatented). The presence of thorns and the size of the fruitdistinguish ‘Chesapeake’ from thornless cultivars such as ‘Arapaho’(U.S. Plant Pat. No. 8,510), ‘Navaho’ (U.S. Plant Pat. No. 6,679), ‘HullThornless’ (unpatented), ‘Triple Crown’ (unpatented) and ‘ChesterThornless’ (unpatented).

ORIGIN OF THE NEW CULTIVAR

The new cultivar of blackberry originated from a controlled cross at theUniversity of Maryland Greenhouses in College Park, Md. The cross “SKNA”was ‘Shawnee’ (U.S. Plant Pat. No 5,686)×R. cunefolius (a wild selectionfrom the town of Crisfeld, Md). This year was designated “N” as part ofthe University of Maryland at College Park; Rutgers University of NewBrunswick, N.J.; Virginia Polytechnic Institute and State University,Southern Piedmont Agricultural Research and Education Center atBlackstone; and the University of Wisconsin at River Falls cooperativebreeding program. The clone was first selected in 1992 at the WyeResearch and Education Center of the University of Maryland located atCenterville, Md. and was therefore designated “−1”. Thus, the completebreeding designation was “NSKNA-1”.

SUMMARY OF THE NEW CULTIVAR

This application relates to a new and distinct thorny, spring bearingblackberry cultivar, botanically known as Rubus argutus×R. cuneifoliusL. The following characteristics are outstanding:

1. Production of fruit which is much larger than the standard cultivarsin use and larger or of equal size to two new extra large cultivars,‘Black Butte’ (unpatented) and ‘Kiowa’ (U.S. Plant Pat. No. 9,861).

2. When compared to all othern eastern blackberry cultivars known to us,‘Chesapeake’ has production of fruit which have a flavor less acid whenslightly immature, at the glossy black fruit stage, allowing a slightblueberry flavor to emerge.

The following characteristics are useful in distinguishing this cultivarand can be useful for cultivar identification.

1. Plants are sparingly suckering and very upright, growing to 12 feetor taller when mature. Canes are only moderately cold hardy, i.e. notrecommended for areas where the minimum winter temperature is less than0° F.

2. Canes, petioles, petiolules and leaf midribs have only a moderateamount of large recurved thorns.

3. The fruit is very large, typically 15-22 grams in the first pickingand has an aroma of a blueberry in cooler temperatures. The flavorcontains undetectable quantities of highly aromatic compounds typical ofeastern U.S. erect thorny or semierect thornless blackberry cultivars.

4. The fruit is produced in the midseason from floricanes. Primocaneproduced fruit is unknown.

BRIEF DESCRIPTION OF THE PHOTOGRAPHS

The accompanying photographs show typical characteristics of the newvariety:

FIG. 1 shows a young ‘Chesapeake’ plant in July 2000, the primocaneheight is 6 feet. The plants are in their second growing season inMillersville, Pa.

FIG. 2 shows the type and density of thorns on the apex of a fluted‘Chesapeake’ primocane.

FIG. 3 shows a ‘Chesapeake’ flowering truss, leaves and the midsectionof a ‘Chesapeake’ primocane.

FIG. 4 shows typical ‘Chesapeake’ flowers.

FIG. 5 shows a fruiting cluster of ‘Chesapeake’, showing unopenedflowers through fruit 3 weeks post pollination.

FIG. 6 shows a fruiting cluster of ‘Chesapeake’ from a two year oldplant in Oak Grove, Va.

FIG. 7 shows several ripe fruit of ‘Chesapeake’.

DESCRIPTION OF THE NEW CULTIVAR

The following is a detailed description of the new cultivar, togetherwith the cultivar's morphological characteristics. The characteristicsof the cultivar were compared to other standards used in theMid-Atlantic Region of the U.S. and a parent, ‘Shawnee’ (U.S. Plant Pat.No. 5,686). The description is based on information provided bycooperating growers and scientists from plants grown in fields at CreamRidge and Colt's Neck, N.J., Millersville, Pa., and Oak Grove, Va., andfrom plants grown in the University of Maryland greenhouses at CollegePark, Md.

‘Chesapeake’ produces a moderate number of root-and crown-suckers,typically 2.7 per plant or 13 per 10 foot of row as measured on 3 yearold plants in Colt's Neck, N.J., similar to ‘Shawnee’ (U.S. Plant Pat.No. 5,686) and other thorny blackberry cultivars tested or grown in theeastern United States. It can therefore be trained as a hedgerow ormaintained as individual plants. During the growing season, primocanesare light green colored (Royal Horticultural Society plate 143B vs. 146Bfor ‘Shawnee’) with a light red blush (Royal Horticultural Society plate59A) in full sun, fluted or moderately grooved, usually branched, veryerect with arching branches and very vigorous (see FIG. 1). InBeltsville, Md. (in full sun), average cane diameter at 10 cm height is11.8 mm and average internode length in the bottom 50 cm of the canes is325 cm. Floricanes are not noticably exfoliating, with only anoccasional narrow split. Floricane color is brown (Royal HorticulturalSociety plate 178A).

In the growing season, primocane thorns are moderate in density, 5 mm inlength and 3.5 mm diameter at their base, sometimes recurved basipetallyand light red (Royal Horticultural Society plate 59A) at the base, butlighter in color (59 B to 59C) and thinner at their apex (see FIG. 2).The red coloration does not extend into the surrounding cane. Pimocaneand floricane leaf adaxial surfaces are dark green, most closely in hueto Royal Horticultural Society Color plate 137A, while the abaxialsurface of the leaf is pubescent giving this surface a greyer color(Royal Horticultural Society plate 147B)(see FIGS. 2 and 3). Leaves aretrifoliate to quinquefoliate and average 14 cm from the distal end ofthe petiole to the distal end of the terminal leaflet. Leaves havetypical blackberry venation patterns with a central vein and severalbranched side veins; however, puckering due to veins is somewhat lessthan other eastern blackberry cultivars. This results in relatively flatleaf laminae. The basal leaflets average 14 cm from terminal point topoint, i.e. opposing leaves below the terminal leaf, on the petioleaverage 14 cm from terminal point of the first leaf to the terminalpoint of the second leaf. The petiole is 5 cm in length and the samelight green color as the cane, Royal Horticultural Society plate 143B.Leaf serration is common for most cultivars of blackberry and cannot beused to distinguish this cultivar.

‘Chesapeake’ floricanes suffer cold injury in mid winter if temperaturesfall below 0° F. Floricanes are not truly exfoliating under conditionstested and the floricanes are purple-brown by mid-winter, resemblingRoyal Horticultural Society plate 178A. Canes can flower from all livebuds in April to May depending on latitude, and fruit from mid June tolate July in the eastern U.S. This ripeness period is 1-2 weeks laterthan ‘Hull Thornless’ (unpatented) and ‘Navaho’ (U.S. Plant Pat. No.8,510), but overlaps ‘Chester Thornless’ (unpatented) and ‘Kiowa’ (U.S.Plant Pat. No. 9,861).

The flower morphology and early fruit morphology is typical of mosteastern U.S. originated blackberry cultivars (the flowers are unscented,5 white petals 1 to 2 cm long with color resembling Royal HorticulturalSociety plate 155D, with a slight pink shading on the opening flowerresembling Royal Horticultural Society Plate 62C; 5 sepals, resemblingRoyal Horticultural Society plate 147B and 3 cm long and which cannot beused to identify ‘Chesapeake’ (see FIG. 4). Flower petals abscise withinseven days post pollination. Early flowers typically containapproximately 90 anthers and 89 pistils. Peduncles are slightly hairyand have the same color as primocanes, Royal Horticultural Society plate143B, and are armed with thorns similar to primocanes, except less thanhalf the size. Peduncles are typically over 2 cm in length.

Fruit trusses are typical cymose clusters with 6 to 15 fruit or morewell spaced out on a truss axis (see FIGS. 5 and 6). Twenty-five daysafter pollination, fruit is distinguishable for this variety by its sizeonly; at this point, unripe fruit is light green (Royal HorticulturalSociety plate 183C). Fruit is dark black internally and externally whenripe, closely resembling Royal Horticultural Society color plate 202A(see FIG. 7). Fruit has little pubescence, producing a glossyappearance. Fruit is decidedly thick elongate (commonly up to 4 cm inlength and 2 cm in width), very large (15-22 gram primary fruit) andsomewhat asymmetrical due to variation in drupelet placement (see FIG.7). Drupelets are held together tightly and the fruit does not“crumble”. Fruit separates when slightly unripe, but does not absciseprematurely. Fruit skin toughness is less than ‘Chester Thornless’(unpatented), but similar to other thorny cultivars such as ‘Shawnee’(U.S. Plant Pat. No. 5,686). The fruit is very “juicy” when crushed andthe drupelets are relatively large. Seed size, including woody endocarp,is large, averaging 4.6 mg per seed fresh weight. Fruit flavor is sweet,even when the fruit is unripe. The torus separates from the plant anddarkens slightly, from white, upon ripening. The fruit does not breakdown after at least one week in common storage at 40° F.; however, somedrupelets will turn dark red upon storage for even a short period oftime (<6 hr). This is typical of blackberry fruit grown in warmclimates. Flavor is sweet (not acid or tart) even when unripe, and notcharacteristic of modern eastern blackberry cultivars, which tend to behighly acid when unripe and “tar-like” when ripe and warm. When grown incooler regions, or during a cooler than normal spring, ‘Chesapeake’fruit has an aroma reminiscent of blueberries.

The plant is field resistant to many of the common pests and diseases inthe eastern United States, e.g. mildew and Phytophthora fragarae rootrot and fruit rot, based on field reaction, not in controlled testing.The plant has not had orange rust or verticillium wilt in several yearsof exposure in the field, but no claim of resistance is made.

‘Chesapeake’ has been asexually reproduced by tissue culture and fieldsuckering since 1994. Over that period, no off-type of ‘Chesapeake’ hasbeen observed or reported to us. Thus, it is concluded that ‘Chesapeake’is stable and reproduced true to type in successive generations ofasexual reproduction. Tissue culture explants originated from lateralbud meristems and multiplication medium contained 3 to 10 micromolarbenzyl adenine. Plants were propagated at South Deerfield, Mass.,Hurlock, Md. and the Department of Natural Resource Sciences, Universityof Maryland, College Park, Md.

What is claimed is:
 1. A new and distinct thorny blackberry plant knownas ‘Chesapeake’ as described herein, illustrated and identified by thecharacteristics set forth above.